This renewal application is for funds to continue operation of the mass spectrometry facility at Michigan State University. Funding is requested to continue to provide the gas chromatograph-mass spectrometer-computer service to investigators at Michigan State University, in the Michigan area, and throughout the country. These services include selected ion monitoring, low resolution mass chromatography, high resolution peak matching and on-line analysis of GC effluent, and solid sample procedures of analysis by electron impact and field desorption mass spectrometry. A quardrupole mass spectrometer with EI/CI source is requested to accommodate the increasing demands for metabolic profiling analyses and to provide chemical ionization capability for sevice work. A table-top "intelligent" minicomputer-controlled gas chromatograph-mass spectrometer is requested for field testing of metabolic profiling in the clinical laboratory at the Michigan State University medical center. This unit will be connected to the time-shared system of the mass spectrometery facility for data processing and profiling analyses. Core research will include the continued development of metabolic profiling, expanding the utility of the technique in support of medical diagnosis of diseases wuch as carcinoid, pheochromocytoma, neural crest tumor, and many inborn errors of metabolism that involve increased excretion of organic acids or steroids. The development of an integrated distributive computing time-shared network will be continued in an effort to maximize the information obtained from single analyses of complex biological mixtures. Investigations of field desorption theory will be continued in an effort to reduce the complexities of this practice to a basic chemical understanding. In addition to the research and service activities, another objective will be to assist in the training of persons who will become professionals in this field as well as those who need added expertise as users.